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Darwin Correspondence Project

To T. H. Huxley   27 May [1865]1

Down. | Bromley. | Kent. S.E.

May 27th.—

My dear Huxley

I have taken a long time to thank you for the Catalogue, the introduction to which I read with much interest.2 The cause has been that I have had a very bad month; but I know begin to hope that through the aid of an acquaintance of yours (Dr Chapman) my health will receive some considerable improvement from the application of ice to the spine.3

I write now to ask a favour of you, a very great favour from one so hard worked as you are. It is to read 30 pages of M.S, excellently copied out, & give me not lengthened criticism, but your opinion whether I may venture to publish it.4 You may keep the M.S. for a month or two. I wd not ask this favour, but I really know no one else whose judgment on the subject wd be final with me.

The case stands thus; in my next book5 I shall publish long chapters on bud—& seminal—variation, on inheritance, reversion, effects of use & disuse &c. I have also for many years speculated on the different forms of reproduction.6 Hence it has come to be a passion with me to try to connect all such facts by some sort of hypothesis. The M.S which I wish to send you gives such a hypothesis; it is a very rash & crude hypothesis yet it has been a considerable relief to my mind, & I can hang on it a good many groups of facts.7 I well know that a mere hypothesis, & this is nothing more, is of little value; but it is very useful to me as serving as a kind of summary for certain chapters. Now I earnestly wish for your verdict given briefly as “Burn it”—or, which is the most favorable verdict that I can hope for, “It does rudely connect together certain facts & I do not think it will immediately pass out of my mind”   If you can say this much & you do not think it absolutely ridiculous I shall publish it in my concluding Chapter.8 Now will you grant me this favour? You must refuse if you are too much over worked—

I must say for myself that I am a hero to expose my hypothesis to the fiery ordeal of your criticism

Believe me my dear Huxley | yours most sincerely | Ch. Darwin


The year is established by the reference to T. H. Huxley and Etheridge 1865 (see n. 2, below).
Huxley sent CD a copy of T. H. Huxley and Etheridge 1865, A catalogue of the collection of fossils in the Museum of Practical Geology, with an explanatory introduction, at the beginning of May (see letter from T. H. Huxley, 1 May 1865). CD had read the proof-sheets of the preface in 1857 (see Correspondence vol. 6, letter to T. H. Huxley, 16 December [1857], and letter to J. D. Hooker, 25 December [1857]).
According to Emma Darwin’s diary (DAR 242), John Chapman visited CD on 20 May 1865. See also letter to John Chapman, 16 May [1865], and Appendix IV. Chapman was proprietor and editor of the Westminster Review, to which Huxley had been a regular contributor (Wellesley index; see also A. Desmond 1994–7, 1: 185).
The copy that CD sent to Huxley has not been found; however, the manuscript from which the copy was made is in DAR 51: C36–74. For a transcript of the original manuscript, which was titled ‘Hypothesis of Pangenesis’, see Olby 1963. This first statement of pangenesis differed in several respects from the version that was later published in chapter 27 of Variation; see Olby 1985, pp. 84–6.
CD refers to Variation, which was published in 1868.
CD’s notebooks and manuscripts indicate that he developed his ideas about heredity and reproduction over a thirty-year period (see Kohn 1980, Hodge 1985, and Olby 1985). For an earlier indication that CD was attempting to develop a hypothesis connecting information on reproduction, see Correspondence vol. 6, letter to T. H. Huxley, [before 12 November 1857]. For a discussion of nineteenth-century debates on heredity and their bearing on the theory of transmutation by natural selection, see Gayon 1998.
The hypothesis of pangenesis that CD outlined to Huxley suggested that each individual cell throws off minute particles (gemmules) that circulate in the bodily fluids and are capable of generating new cells, or remaining dormant until required. The gemmules are drawn together by mutual attraction and into the right places in the right order to, for instance, reconstruct (in organisms that have that capability) a tail or other limb where one has been torn off. Cells throw off gemmules at all stages of development and all gemmules circulate until required: thus embryo gemmules thrown off by embryo cells come together, when conditions are right, to form what CD called the germ (the female element) or the male element; the germ, if fertilised (or even if not, in the case of parthenogenesis), grows into a new embryo (see Olby 1963). Gemmules could also remain dormant for several generations before being sparked into activity. Thus CD thought pangenesis could explain both sexual and asexual reproduction, as well as reversion and the regrowth of body parts. For a discussion of the development of the hypothesis of pangenesis during the 1860s and the part played by CD’s contemporaries, including Herbert Spencer, Charles Victor Naudin, and Richard Owen, in shaping it, see Geison 1969.
The manuscript discussed here was expanded and revised before being published in the penultimate chapter of Variation, ‘Provisional hypothesis of pangenesis’ (Variation 2: 357–404).


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.

Desmond, Adrian. 1994–7. Huxley. 2 vols. London: Michael Joseph.

Gayon, Jean. 1998. Darwinism’s struggle for survival: heredity and the hypothesis of natural selection. Translated by Matthew Cobb. Cambridge: Cambridge University Press.

Geison, Gerald L. 1969. Darwin and heredity: the evolution of his hypothesis of pangenesis. Journal of the History of Medicine 24: 375–411.

Hodge, M. J. S. 1985. Darwin as a lifelong generation theorist. In The Darwinian heritage, edited by David Kohn. Princeton, N.J.: Princeton University Press in association with Nova Pacifica (Wellington, NZ).

Kohn, David. 1980. Theories to work by: rejected theories, reproduction, and Darwin’s path to natural selection. Studies in History of Biology 4: 67–170.

Olby, Robert. 1963. Charles Darwin’s manuscript of pangenesis. British Journal for the History of Science 1: 251–63.

Olby, Robert. 1985. Origins of Mendelism. 2d edition. Chicago and London: University of Chicago Press.

Variation: The variation of animals and plants under domestication. By Charles Darwin. 2 vols. London: John Murray. 1868.

Wellesley index: The Wellesley index to Victorian periodicals 1824–1900. Edited by Walter E. Houghton et al. 5 vols. Toronto: University of Toronto Press. London: Routledge & Kegan Paul. 1966–89.


Thanks for Catalogue.

Has had a bad month. Somewhat improved as a result of John Chapman’s ice-bag cures.

Asks THH to read MS on his hypothesis Pangenesis. THH only man whose judgment on it would be final with him.

Letter details

Letter no.
Charles Robert Darwin
Thomas Henry Huxley
Sent from
Source of text
Imperial College of Science, Technology and Medicine Archives (Huxley 5: 214)
Physical description
LS(A) 5pp

Please cite as

Darwin Correspondence Project, “Letter no. 4837,” accessed on 21 July 2024,

Also published in The Correspondence of Charles Darwin, vol. 13